The present invention relates to an ultrasound diagnostic apparatus for calculating a functional index from a motion rate of a cardiac muscle and ultrasound image processing apparatus.
An objective and quantitative evaluation of a cardiac motion, that is, contracting and dilating motions, is very important to the heart diseases. As the quantitative evaluation method there are the left-ventricular wall motion analytic method, stress echo method, etc. However, the left-ventricular wall motion analytic method, etc., is one special to ischemic cardiac diseases and has no general applicability.
Further, the left-ventricular wall motion analytic method comprises finding a cardiac muscle thickness from a tissue cross-sectional image (B-mode image) and calculating a temporal variation in the cardiac muscle thickness and provides no objective basis. Further, the left-ventricular motion analytic method cannot calculate the index relating to the longitudinal-axis direction of the heart.
Such a problem can be solve by what is called a segment shortening method. This method comprises embedding a plurality of strong reflectors (for example, crystals) in the cardiac muscle and very much highly accurately measuring the motion function of the heart by tracing the positions of these strong reflectors. This segment shortening method is highly dangerous and has been thought impossible to apply it to a human being. In the present time, it may be said that there is no method for measuring the motion function of the heart with a precision equal to that of the segment shortening method.
In order to measure the motion function of the heart with high precision, it is very important to investigate the motion directions (contracting and dilating directions) of the heart. These motion directions not only differ in each part of the heart but also constantly vary in the same part. It is, therefore, impossible to measure the motion function of the heart very accurately.